I have solved this once in the past, it's just been so long I can't remember how, and can't find anything. My horizontal scrolling action is working in Kubuntu/KDE, as I can use horizontal scrolling where it's appropriate. Using xset and such is a workaround I've tried before, but the problem with using that is no matter where I am, horizontal scroll action is triggered.

My goal is to enable horizontal scroll action in the Desktop Settings for mouse actions, so that when the cursor is over the desktop, and I click the left/right of the scroll wheel, I can change desktops. Right now, horizontal scroll is not captured when I try to set it there.

Does anyone know how this can be set? I am running Kubuntu 15.04 on Plasma 5.3.1 + KDE apps 15.04 from the backports. FYI, running the "default" Plasma out-of-the-box has the same issue.